Such electromagnetic screening is generally achieved by means of a metal cover closed over the substrate.
At present, two main types of techniques are used to fit such a cover.
According to a first type of solution, the electrical connection of the metal cover to ground which the metal substrate constitutes is formed independently of the mechanical fixing of the cover with respect to the substrate and to the electronics card. For example, the electrical connection to ground may then be formed by means such as riveting, or screwing a soldered joint or even a soldered wire link.
In a second type of solution, the metal cover is fixed mechanically to the substrate by means of an adhesive which is made from an electrically conducting material and which carries out the electrical connection function.
However, these two types of solutions both exhibit drawbacks.
In particular, the solutions in which the mechanical fixing and electrical connection are achieved by different means require additional operations during manufacture and are expensive.
Moreover, with these solutions, the leaktightness between the metal cover and the substrate is not generally assured.
Equally, the solutions in which a conducting adhesive are used also carry a high cost particularly because of the operation of applying a bead of adhesive.
Moreover, with these solutions, the adhesive joints pose problems of behaviour over time, as well as of response to temperature and to vibration.